wheel bit: n. A privilege bit that allows the possessor to
perform some restricted operation on a timesharing system, such as
read or write any file on the system regardless of protections,
change or look at any address in the running monitor, crash or
reload the system, and kill or create jobs and user accounts. The
term was invented on the TENEX operating system, and carried over to
TOPS-20, XEROX-IFS, and others. The state of being in a privileged
logon is sometimes called `wheel mode'. This term entered the Unix
culture from TWENEX in the mid-1980s and has been gaining popularity
there (esp. at university sites). See also root.